What is the significance of CSS in web development?

The significance of CSS (Cascading Style Sheets) in web development lies in its primary role of defining the visual style of web pages. CSS allows developers to separate content from presentation, which means that they can maintain the content (HTML) independently of how it is visually displayed. This separation enhances maintainability, as design changes can be made in the CSS file without altering the underlying HTML structure.

With CSS, developers can control various style properties, such as colors, fonts, layouts, spacing, and responsiveness, ensuring that web pages are not only visually appealing but also adaptable to different screen sizes and devices. This flexibility is crucial in today's landscape of diverse devices accessing the web.

While creating interactive user interfaces is important, it is generally the realm of JavaScript rather than CSS, which is focused on style rather than behavior. Additionally, managing server-side logic and enabling client-server communication are responsibilities belonging to server-side programming languages and protocols, not to CSS. Thus, the correct answer emphasizes CSS's critical function in defining how content is visually presented on the web.